Electric discharge lamp starting device



Nov. 2, 1943. THOMAS 2,333,215

ELECTRIC DISCHARGE LAMP STARTING DEVICE Filed April 27; 1942 Fig.2

I hOMtZS INVENTbR.

-.yazi mm ATTORNEY.

Patented Nov. 2, 1943 ELECTRIC DISCHARGE LAMP STARTING DEVICE Ralph B.Thomas, Beverly, Mass, assignor to Sylvania Electric Products Inc., acorporation oi Massachusetts Application April 27, 1942, Serial No.440,744

2 Claims.

This invention relates to electrical circuit relays and moreparticularly to relays for regulating the electrode pre-heating periodof electric gaseous discharge lamps.

An object of this invention is to provide a fluorescent lamp starterswitch which will not only operate to provide a pre-determined heatingperiod for the filamentary electrodes but will also automatically arrestits operation in this respect when'for any reason the lamp fails tolight after a number of unsuccessful attempts.

Another object is to provide a starter switch which will accomplish thisarresting operation without putting a strain on the several elementswhich go to make up the switch or the auxiliary starting apparatusemploye in conjunction therewith.

Further objects, advantages and features will be apparent from thefollowing specification taken in conjunction with the accompanyingdrawing in which:

Figure 1 is a front view of the relay of my invention removed from thecontainer in which it is normally enclosed.

Figure 2 is a schematic diagram of said relay and the circuit inconjunction with which it may be used.

In the operation of electric gaseous discharge tubes and moreparticularly in the operation of fluorescent lamps, a relay is generallyemployed to permit the pre-heating of the filamentary electrodessuilicient to effect a striking of the lamp are. If the lamp arc failsto strike or maintain,

the relay operates to provide a second period of In this regard I haveelectrode pre-lieating. found that the thermal relay shown in thecopending application, Serial Number 335,968, filed May 18, 1940, to beof distinct advantage for it provides an auxiliary starting means whichoperates when the lamp arc fails to strike or maintain in the firstinstance. A further improvement in thermal relays is embodied in thecopending application, Serial Number 417,544, filed November 1, 1941. Inthis application the relay includes a cut-out feature which arrests theoperation of the relay elements if the lamp is faulty. This is a highlydesirable feature for it not only eliminates the unsightly appearancewhich a defective lamp presents when the arc fails to strike despite thesuccessive pre-heating cycles but it also prevents any undue strainbeing placed on the auxiliary equipment under said conditions. A furtherimprovement in that type of relay is embodied in the present invention,the distinctive features of which will be apparent from its description.

In Figure 1, the resistance rod 2 is mounted on the support I throughthe wires 3 and 4.

Electrical connection through the base pin 8 to the wire 3 is madethrough the metallic strip 1 which runs up the back of the support I.The arm l4, extending inwardly from the point; at which it and the wire3 are attached to the support l by eyelets, soldering or some similarmeans, has attached thereto one end of the bimetallic armature [3 whichis bent around the resistance rod 2.. The free end of this bimetal I3 isnormally closed with the contact l5 of'high contact resistance. Thistype of resistance may be obtained by utilizing carbon or some similarmaterial as the contact itself or a resistance in series with a contactmay be used to obtain the same effect. This carbon contact I5 is mountedon the outer end of a U-shaped arm I! which is supported at its innerend from the bimetallic com.- pensator I6. This compensator I6 ismounted on the support I through the arm I9. The free end of thiscompensator It, i. e., the end from which the U-shaped arm I! is mountedhas fixed thereon a contact l8 of low contact resistance, such as silverfor example. This contact element I8 is in contact relationship with thefree end of the bimetallic strip l3 under certain operating conditions.The bimetallic element l6 serves to compensate for ambient temperaturechanges, thus automatically insuring proper spacing and proportioning ofthe contact elements of the relay under varying operating conditions.The aim Hi to which an end of the compensator I6 is fixed has an endthereof electrically connected to the lead-in wire extending up throughthe relay base from the contact pin 5. The wire 9, on which theresistance rod 8 is mounted, has one end thereof electrically connectedto this same leadin wire extending up from the contact pin 5. This wire9 extends upwardly along the longitudinal axis of the support I, itsother end being electrically connected to the Wire 4 The wire 9 hasmounted at each end thereof bimetallic elements I0 and l l extendingtowards each other. The bimetal l0 serves as an armature, the bimetal llbeing its compensator. These two elements are nornially closed with eachother through the contact 2.

In Figure 2, the electric gaseous discharge lamp 2D has the filamentaryelectrodes 2| and 22 sealed in the ends thereof. One end of theelectrode line 24, the other end thereof being connected to the relay ofFigure 1 through the base pin 5. One end of the electrode 22 isconnected to the other end of the power line 24 through a suitableballast impedance, such as an inductance coil 23. The other end ofelectrode 22 is connected to the relay through the base pint.

The circuit through the relay will be through elements 5, I6, I5, I3, 3,I, and 6, elements II, I2, I0, land 2 being connected in paralleltherewith. Thus the contact I2 in the cut-out opens a circuit carryingonly a very small current passed by the high resistance rod 2. Under.ordinary conditions of lamp operation, the circuit through II, I2 andIll remains closed, the high resistance rod 8 being short-circuitedthereby.

Under failed lamp conditions the pre-heating cycle is repeated a numberof times and the heat developed in the high resistance rod 2 isconsiderably greater than during normal lamp-starting and operatingconditions. Enough of this heat will be conducted through the wire 4 tothe bimetallic armature ID to distort it suificiently to open thecircuit through II, I2 and III. The opening of this circuit places thehigh resistance rod 8 in series with the high resistance rod 2.

Once this condition obtains, the resistance rod 8 develops enough heatto keep open the circuit through II, I2 and I. This is especially true Ibecause of its location with respect to the armature I0 and thecompensator I2. As may be noted from Figure 1 of the drawing, theresistance rod 8 is not located in the longitudinal center of the wire 9but at a point considerably removed'from the point at which thecompensator II is mounted thereon. It is mounted directly adjacent tothe armature l0 so that substantially all of the heat generated by thecircuit therethrough will be concentrated by conduction, radiation, orconvection on the armature Ill rather than on the compensator I I. Thisheat from the resistance rod 2 as is conducted through wire 4 willsufiiciently distort the armature Ill to keep the circuit through I0,l2, and II open.

' to each other under dead circuit conditions.

Although I have illustrated my cut-out in a manner in which it may bestbe utilized with a thermal relay, it must be readily understood thatthis cut-out may well be adapted for use with a glow relay withoutdeparting from the spirit of this invention. Thus, for example, when arelay of the thermal type is used, the relay and the resistor 2 would beconnected in parallel wit respect to each other and together they wouldbe connected in series with the cut-out.

What I claim is: I

1. A starting unit for an electric gaseous discharge device, said unitcomprising: A plate-like base of insulating material; a panel ofinsulating material mounted on said base; a pair of contact pinsextending from one side of said base; a pair of lead in wires, eachconnected to one of said contact pins and extending from the other sideof said base; a switch assembly mounted on said panel in connection withsaid lead in wires and including a heater element, a hook-like thermallyresponsive member electrically connected to one of said lead-in wiresand. mounted with said heating element lying within the loop portion ofsaid hook, and a contact assembly electrically connected to the other ofsaid lead-in wires and including a supporting arm and a contact member,with said thermal member in normally closed relation with said contactmember; and a second switch assembly connected with the heating elementof said first named switch assembly and one of said lead in wires andincluding a heating element and a thermally responsive member arrangedto short circuit said last named heating element when said member isunheated.

2. A starting unit for an electric gaseous discharge device, said unitcomprising: A plate-like base of insulating material; a panel ofinsulating material mounted on said base; a pair of contact pinsextending from one side of said base; a pair of lead in wires, eachconnected to one of said contact pins and extending from the other sideof said base; a switch assembly mounted on said panel in connection withsaid lead in wires and including a heater element disposed horizontallyacross said upright, a hook-like thermally responsive member mountedwith said heater element lying within the loop portion of said hook,

' and a contact assembly electrically connected to the other of saidlead-in wires and including a supporting arm and a pair of spacedcontact arms mounted thereon with a contact on each, with said thermalmember electrically connected to one of said lead-in wires in normallyclosed relation with one of said contact members and disposed betweensaid contacts; and a second switch assembly connected with the heatingelement of said first named switch assembly and one of said lead inwires and including a heater elementv disposed vertically along an edgeof said upright and a thermally responsive member arranged toshort-circuit said last named heater element when said member isunheated, said last named thermal member being disposed within theheating range of said horizontal heater element.

RALPH B. THOMAS

